A picture of a half-eaten mako shark caught off the Far South Coast of NSW has left people wondering.
While many are awed by the size of the shark head itself, others are incredulous at what else must be in the water that was able to attack and eat the large predator.
People's interest in the wonders of the ocean has seen the photograph, taken by NSW South Coast commercial fisherman Jason "Trapman" Moyce, receive over 24,000 comments and 14,000 shares on Facebook in just 16 hours, many in awe of the 100kg head.
The image shows Mr Moyce's 18-year-old employee of just three weeks Jasper Lay holding the head of the shark, estimated to have been up to 300kg before being eaten, aboard a boat.
They must fight, because you just can't picture how it would happen.
While the pair didn't see what had attacked the shark, Mr Moyce assumed it was either a great white shark or a tiger shark, which he describes as "the garbage trucks of the sea".
"Jasper didn't realise sharks were that big, but even at that size it's only half grown," Mr Moyce, from Bermagui, said.
The mako shark is an efficient predator in its own right, and is known for its fast speeds and ability to jump into the fishing boats.
While the post has drawn attention from media outlets across the world keen to interview Mr Moyce, he said it is a common sight out on the open water.
"This time of year it is common. Over summer there's more great whites and tiger sharks around," Mr Moyce said.
"I don't shark fish every week, but I would see it every week if I did. Some people don't see this kind of thing or expect it is possible."
What Mr Moyce found even more interesting was the marlin bill the pair later discovered embedded just below the shark's gill slits.
"It was actually sticking into its throat, so anything it was eating had to pass by it," he said.
"It had grown over and must've been there for some years. It shows how amazing sharks are, being able to heal like that."
In 2015 Mr Moyce caught a 120kg mako shark with a marlin bill pierced entirely through its body.
"They must fight, because you just can't picture how it would happen," he said.
"Larger sharks could be looking for marlin to eat. You just can't imagine what goes on under there."
Mr Moyce said the heads of sharks are often left behind due to the animal's sharp teeth.
"The head is full of teeth, it's the hardest part of a shark's body so it's left alone," he said.
A 3.2 metre long tiger shark was tagged and released at a NSW Department of Primary Industries drumline just north of Tura Head.
"I don't shark fish much because of that reason, that they can be that size," Mr Moyce said.
In March the drumlines have also caught a 1.82 metre great white shark, and two tiger sharks off Tathra Beach, but Mr Moyce said he feels they make no difference to the safety of swimmers.
"I call it the placebo effect," he said. "I don't think it makes a difference in saving someone's life.
"It's just about mind over matter for some people. Most sharks aren't looking to eat people."
Last year a video taken by Mr Moyce of four single-use plastic bags being pulled from the stomach of an emaciated tiger shark added weight to a push for a blanket ban on the bags in Australia.
The video had more than 300,000 views.
"I recorded it to document this kind of thing. The word needs to get out," Mr Moyce said at the time.
"This region is supposed to be pristine and non-polluted. If this is happening, what chance has the ocean got?
"There's not many things that aren't made out of plastic these days."